BEC-BCS crossover in an optical lattice

Arnaud Koetsier, D. B. M. Dickerscheid, H. T. C. Stoof

Published 2006-04-06, updated 2006-09-29Version 2

We present the microscopic theory for the BEC-BCS crossover of an atomic Fermi gas in an optical lattice, showing that the Feshbach resonance underlying the crossover in principle induces strong multiband effects. Nevertheless, the BEC-BCS crossover itself can be described by a single-band model since it occurs at magnetic fields that are relatively far away from the Feshbach resonance. A criterion is proposed for the latter, which is obeyed by most known Feshbach resonances in ultracold atomic gases.